ath9k: release allocated buffer if timed out

In ath9k_wmi_cmd, the allocated network buffer needs to be released
if timeout happens. Otherwise memory will be leaked.
Signed-off-by: Navid Emamdoost <navid.emamdoost@gmail.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/ath/ath9k/wmi.c

@@ -336,6 +336,7 @@ int ath9k_wmi_cmd(struct wmi *wmi, enum wmi_cmd_id cmd_id,
 		ath_dbg(common, WMI, "Timeout waiting for WMI command: %s\n",
 			wmi_cmd_to_name(cmd_id));
 		mutex_unlock(&wmi->op_mutex);
+		kfree_skb(skb);
 		return -ETIMEDOUT;
 	}